Last week, at Facebook’s “roadmap edition” of the Facebook Developer Garage, the company announced a series of large changes to the Platform (19 to be exact). Today, the company just released an FBML Bookmark button, and posted a few more details on the new “Counter” API. Here are the details:

1) FBML Bookmark

Many developers have devoted large chunks of their canvas pages to try to get users to bookmark their app by clicking the “bookmark” button in the bottom menu bar of the site. Today, Facebook released an FBML and XFBML tags that developers can use to put the button anywhere on their canvas pages. This should increase bookmarking rates.

When users click the button, they’ll see the following popup:

Facebook adds, “We may experiment with changing the wording on this button (for example, ‘Add to Home page’) when the bookmark location moves, but enabling users to easily return to the applications that they love will still be a core part of their experiences with applications.”

2) Counter API

Facebook hasn’t said much about the Counter so far, other than developers will have the option to display a number on a user’s application bookmark on the home page “to indicate to a user that they should take an action in your application,” and that “when a user clicks through to the application, the Counter will be reset to zero.”

Today, Facebook added that the counter “will likely be located beside all applications on the Application and Games Dashboards as well,” and that the Facebook Platform team is “still designing exactly how Counters will be displayed beside non-bookmarked apps. Stay tuned.”